Zee Flashcards
(29 cards)
The diagram below shows a plank being used as a simple machine.
The crate is slid up the plank into the back of the lorry.
crate
(70kg)
0.5m
The mass of the crate is 70kg. Calculate the weight of the crate.
70 * 9.8 Weight = 686 N
The diagram below shows a plank being used as a simple machine.
The crate is slid up the plank into the back of the lorry.
crate
(70kg)
0.5m
Calculate the work done when the crate is lifted a vertical distance of 0.5m.
(4)
Work done = force * distance
Work done = 686 *0.5
343 joules
Q2.
A forklift truck was used to stack boxes on to a trailer.
It lifted a box weighing 1900 N through 4.5 m.
Calculate the work done on the box. Show your working.
Work Done = Force * Distance
Work Done = 1900 * 4.5
= 8550 j
Work done = 8550 J
Q3.
A rollercoaster car stops above a vertical drop. Suddenly it falls under gravity.
The drop is 60 metres high and at the bottom of the drop the car travels at 125 km/h.
The acceleration experienced by the people in the car is 10 m/s2. The mass of the
car and its passengers is 1210 kg.
Calculate the force exerted on the car and its passengers. Show your working out.
Force=1210 * 10 =12,100 N
Force = 12100 N
- Simplify:
square root 20
Factorize 20: 20 = 4 * 5
Take the square root of 4: sar.rt(4) = 2
simplify 6 square root 2
Factorize 72: 72 = 36 * 2
Take the square root of 36: square root(36) = 6
Simplify: 3sqr rt(12) + 2sqr rt(27)
Break down each term:
sar rt(12) = sarrt(4 * 3) = 2sqr rt(3)
sar.rt(27) = sar.rt(9 * 3) = 3sqr rt(3)
Substitute back:
3(2sqr rt(3)) + 2(3sqr rt(3))
Multiply:
6sqr rt(3) + 6sqr rt(3) = 12square root(3)
- Simplify: 5sqr rt(3) - 2sqr rt(3)
Both terms have sqr.rt(3), so subtract the coefficients:
(5 - 2)sqr.rt(3) = 3sqr rt(3)
Simplify: sar rt(18) + sar rt(50)
Break down each term:
sar.rt(18) = sar.rt(9* 2) = 3sqr rt(2)
sar.rt(50) = sar.rt(25 * 2) = 5sqr rt(2)
Combine like terms:
3sqr rt(2) + 5sqr rt(2) = 8sqr rt(2)
Expand and simplify: (sar.rt(5) + 2)(sgr.rt(5) - 3)
Use the distributive property (FOIL method):
I(sar.rt(5) * sar.rt(5)) + (sar.rt(5) * -3) + (2* sar.rt(5)) + (2 *- 3)
.
5 - 3sgr rt(5) + 2sqr rt(5) - 6
.
Calculate each term:
.
Simplify:
(5 - 6) + (-3sqr rt(5) + 2sqr rt(5))
-1 square.root(5)
Expand and simplify: (2sqr rt(2) + 1)(square root(2) - 4)
.
Use the distributive property (FOIL method):
(2sqrf:(2) * sar.rt(2)) + (2sqr rt(2)* -4) + (1* sar.rt(2)) + (1 *- 4)
Calculate each term:
2(2) - 8sqr rt(2) + sar.rt(2) - 4
Simplify:
(4 - 4) + (-8sqr rt(2) + sar.rt(2))
-7sqr rt(2)
Rationalise the denominator of: 1 / sqr rt(7)
square root 7/7
(a) Figure 2 shows how the activity of the radium-226 will change.
Determine the half-life of radium-226.
1600
Radium-226 was discovered by Marie Curie in 1898.
The notebooks she used were contaminated with radium-226 and are still hazardous.
Explain why the notebooks are still hazardous.
It still gives off harmful radiation.
Explain how the properties of α, β and γ radiation affect the level of the hazard at different distances.
- Alpha (a): Dangerous close up but stops at paper or skin.
- Beta (ß): Travels a few meters, goes through skin, but metal stops it.
- Gamma (v): Travels far, passes through most things, and needs thick lead or
concrete to block it.
Alpha particles, beta particles and gamma rays are types of nuclear radiation.
(a) Describe the structure of an alpha particle.
2 protons and 2 neutrons
Alpha particles, beta particles and gamma rays are types of nuclear radiation.
Nuclear radiation can change atoms into ions by the process of ionisation.
(i) Which type of nuclear radiation is the least ionising?
gamma rays
Alpha particles, beta particles and gamma rays are types of nuclear radiation.
What happens to the structure of an atom when the atom is ionised?
no balance between protons and neutrons
People working with sources of nuclear radiation risk damaging their health.
State one precaution these people should take to reduce the risk to their health.
lead lined clothing
Smoke alarms contain an alpha radiation source and a radiation detector. The smoke alarm stays off while alpha radiation reaches the detector.
Why does the alarm switch on when smoke particles enter the plastic casing?
The alarm turns on because smoke blocks the alpha radiation, stopping it from
reaching the detector. This reduces the electric current, triggering the alarm.
Smoke alarms contain an alpha radiation source and a radiation detector. The smoke alarm stays off while alpha radiation reaches the detector.
Why is it safe to use a source of alpha radiation in a house?
Alpha radiation is safe because it can’t pass through the plastic casing and doesn’t
travel far in air.
The smoke alarm would not work with a radiation source that emits beta or gamma radiation.
Explain why.
Beta and gamma radiation wouldn’t work because they can pass through smoke, so
they wouldn’t cause a drop in current to trigger the alarm.
The smoke alarm switches on when the count rate falls to 80 counts per second.
Explain why the radiation source inside the smoke alarm should have a long half-life.
The source needs a long half-life so it keeps working for years without needing
replacement. If it decayed too quickly, the alarm would stop working properly.
Explain the ideal properties of a radioactive source for use in medical diagnosis.
The source should give off gamma rays (so it can be detected outside the body), have a
short half-life (so it doesn’t stay in the body too long), be safe for the patient, and decay
into something harmless.
